- 2072 Chaitra · 4 marks
Flynn's classification
Short answer
Flynn's classification groups computers by instruction and data streams: SISD (single instruction, single data), SIMD (single instruction, multiple data, e.g., array processors), MISD (multiple instructions, single data, rare), MIMD (multiple instructions, multiple data, e.g., multicore).
Describe Flynn's classification.
Flynn's classification groups computers by the number of instruction streams and data streams they handle at the same time.
| Class | Instruction streams | Data streams | Example |
|---|---|---|---|
| SISD | Single | Single | Conventional uniprocessor (von Neumann) |
| SIMD | Single | Multiple | Array/vector processors, GPUs |
| MISD | Multiple | Single | Rare; fault-tolerant or systolic arrays |
| MIMD | Multiple | Multiple | Multiprocessors, multicomputers, multi-core |
SISD: CU --> PU <--> Memory
SIMD: CU --> PU1 <-> M1
+-> PU2 <-> M2 (one instruction, many data)
+-> PUn <-> Mn
MISD: CU1 -> PU1 \
CU2 -> PU2 >--> one data stream through all
CUn -> PUn /
MIMD: CU1->PU1<->M1 ; CU2->PU2<->M2 (independent, via network)
- SISD: one instruction executed on one data item at a time; may use pipelining.
- SIMD: all processing units execute the same instruction on different data, in lock step.
- MISD: different instructions operate on the same data stream; practically little used.
- MIMD: each processor runs its own program on its own data; tightly coupled (shared memory) or loosely coupled (distributed memory).
✓ Answer checked by Claude Opus 5.5 (high effort)
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